Cursor not unlocking in PC release or development build

I have done some poking around for several weeks now, and just cant seem to figure out why cursors aren’t unlocking? It is strange, because scripts that should normally work for locking/unlocking (and did before), don’t now. I am using the latest version of Unity. Is this a known bug?

You could do this:

        //put in function update ()
        if(Input.GetKeyDown("whatever button you want to press in order for the cursor to unlock"))
        {
                Screen.showCursor;
        }

        if(Input.GetKeyDown("whatever button you want to press in order for the cursor to lock"))
        {
                Screen.lockCursor;
        }